This is a WW II Japanese Army ammo crate. Because of the dividers inside, I believe it was used for cartridge cases for an anti-aircraft gun. It is a heavy duty case and has two heavy chains on the backside, which were probably used to hang it on a gun carriage for transporting. If you look close at the postmark, you will see it is dated November 23rd 1943. The Marine that mailed it home nailed a piece of scrap wood on the top of the case and printed the address and the contents of the box on the piece of wood. I bought this years ago when I was living in Chicago. When I looked closely at the address, I found that this box had been shipped to an apartment building only three blocks from where I was living at the time.